Born in Canada, Isobel Miller studied at Moody Bible Institute, Chicago. She went to China with the China Inland Mission because of the influence on her life of J. O. Fraser. Shortly after her arrival, she married her fiancé, John Kuhn, and eventually they were assigned to work in west Yunnan, among the Lisu people, a minority nationality in southwest China.
She played a key role in establishing the Rainy Season Bible Schools among minority peoples, in translating the Lisu New Testament, and in ministering to the needs of Lisu women. She and her husband helped the Lisu Christians resist the efforts of the Japanese to advance east of the Salween River into west China as they attacked from Burma. Unsettled conditions in west China in the late 1940s made it necessary for Isobel and her family to leave China. They continued their ministry among the Lisu in northern Thailand from 1951 to 1954. She went to the United States in 1954 to treat the cancer from which she died in 1957.
During the course of her missionary career she wrote eight books that enjoyed great popularity among the Christian public. Among these were Ascent to the Tribes (1956), Nests above the Abyss (1947), Green Leaf in Drought Time (1957), and Stones of Fire (1960).